If seven coins are flipped what is the probability of obtain

If seven coins are flipped, what is the probability of obtaining at least one tail?

Solution

P(at least one tail) = 1 - P(no tails)

That is,

P(at least one tail) = 1 - P(all heads)

Thus,

P(at least one tail) = 1 - P(all heads) = 1 - (1/2)^7

= 0.9921875 [ANSWER]